Hash images

Now, this is what I call cool: findimagedupes.

It's a image hashing program, that outputs a "perceptual hash" of image files. Unlike a cryptological hash, a small change in an image should result in a small change, so you can use this to tell how similar two slightly different images are.

You can also use it to recursively search directories for duplicate images.

It's in apt for debian and ubuntu.